Conventional audio systems, for example, in the form of automobile radio units sold by the firm Blaupunkt-Werke GmbH, Hildesheim, Del., are able to reproduce audio signals from various sources, such as from a radio receiver or a compact disk player or a compact cassette player. Such audio systems may allow the reproduction of the audio signals optionally either from a first source, such as the radio receiver, or from a second source, such as the CD player or the CC player. Simultaneous reproduction of the audio signals from various sources is not provided in such units. Thus, for example, during playback of a CD or CC, in case traffic information is received by the use of the radio receiver, the CD or CC playback is interrupted, instead of it the traffic information is reproduced, and subsequently the CD or CC playback is resumed.